The present invention relates to a locking synchronizer for a gear transmission of a motor vehicle, having loose and fixed gears. The synchronizer has a shift sleeve non-rotatably mounted on a guide sleeve but axially displaceable with tensioning of a snap ring. The shift sleeve has shift teeth for engaging corresponding shift teeth on a loose gear on a conical surface directed radially inward for Cooperation with the outer cone of a synchronizing ring. The synchronizing ring is equipped with a plurality of claws distributed symmetrically around the circumference and projecting radially inward. The claws engage broad gaps between the shift teeth of the loose gear, these gaps being formed between the shift teeth of the loose gear by removing one or more teeth. The synchronizing ring is rotatable to a limited extent and the gaps between the teeth of the loose gear.
A locking synchronizer of this general type is shown in German Published Examined Patent Application No. 2 059 218. In that synchronizer, a guide sleeve is mounted on a drive shaft. A concentric inner shift toothing of a shift sleeve engages the outer toothing of the guide sleeve in such a manner that it is non-rotatably but axially displaceable relative to the guide sleeve. When shifted lengthwise the shift toothing on the shift sleeve engages a corresponding shift toothing mounted on an annular projection of the loose gear to be engaged. Previously, however, the loose gear is synchronized with the shift sleeve by a synchronizing ring disposed therebetween. The outer cone of the synchronizing ring is in frictional contact with the inner conical surface of the shift sleeve.
At the same time, projections on the synchronizing ring which project radially inward engage matching recesses provided in the annular projection on the loose gear. The shifting motion of the shift sleeve and the synchronizing ring is counteracted by a snap ring which is inserted in an annular groove, open toward the inside, in the extensions and abuts the inner conical circumferential surface of the annular projection under spring tension.
The disadvantage of this synchronizer is the large structural width required for the annular projection with its conical circumferential surface. In addition, after manufacturing the toothing to receive the projections, deep and precisely dimensioned recesses and pockets must be machined in the loose gear after the toothing is produced, making manufacture considerably more difficult and expensive.
An object of the present invention is to reduce the structural width of a locking synchronizer and to simplify its manufacture.
This and other objects are achieved in the present invention by providing in a locking synchronizer having a synchronizing ring equipped with a plurality of claws distributed symmetrically around the circumference and projecting radially inward, with claws having conical inner circumferential surfaces which radially tension a snap ring during a lengthwise displacement of the synchronizing ring. A feature of a preferred embodiment provides a synchronizing ring with locking surfaces on either side of the claws and delimiting of the loose gear tooth gaps by deflecting surfaces on the loose gear shift teeth so that the locking surfaces cooperate with the deflecting surfaces. A further feature of a preferred embodiment of the present invention provides that the loose gear shift teeth are formed on an annular projection of the loose gear, so that the synchronizer has an axial width equal to the annular projection.
Because the snap ring is compressed by the conically tapering inner circumferential surfaces of the claws mounted on the synchronizing ring, the conical inner circumferential surfaces on the annular projection of the loose gear can be eliminated, so that the loose gear can be made narrower. The loose gear is simpler to manufacture since only one annular groove is cut from the outside in its annular projection to guide the snap ring. In this groove, the snap ring is movable under radial spring tension with lateral play. By providing finished recesses, the need to create tooth gaps when cutting teeth is eliminated.
In order to lock the shift sleeve in its right-hand or left-hand engaged position under load and to avoid jumping out of qear, provision is made to make engagement angles .alpha.1 and .alpha.2 between their shift teeth and the outer teeth on the guide sleeve appropriately different. A locking device of this kind is described in German Pat. No. 2,523,953. It can be used especially advantageously in combination with the invention since in this way the backing for the shift teeth on the loose gear and the shift sleeve can be eliminated.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.